Now, just as Graham was looking to further establish his reputation as the Bucs' workhorse running back, his own injury threatens to cut his season short and leaves the Tampa Bay backfield without its centerpiece.

An unspecified ankle injury Graham suffered on his first carry Sunday against the Vikings has left his season "in jeopardy," coach Jon Gruden said Monday. The Bucs were just beginning to reassemble their backfield after getting fullback B.J. Askew back from a torn hamstring.

"I think Earnest Graham is one of the most underrated backs in the league," center Jeff Faine said. "We'll just have to depend on the guys we have coming back to get it done. But it can't go unsaid that Earnest Graham is definitely a great short-yardage back, a great goal-line back and a great all-around back. It'll be a big loss for us."

With the 7-3 Bucs cautious about asking veteran Warrick Dunn to carry an excessive workload, it's likely Cadillac Williams will enter the picture in some capacity Sunday at Detroit.

Clifton Smith's string of fumbles perhaps increases the likelihood the Bucs will lean heavily on Williams, who hasn't played since September 2007 and was activated from the physically-unable-to-perform list just last week after completing his comeback from a torn right patellar tendon.

"I'm ready," Williams said. "I've put in a lot of work, and I feel confident. I'm mentally ready and physically ready. I just hate that the situation had to come like this, with (Graham) going down. But that's football. I'll make the best out of the opportunity."

And it's a big one. With the Bucs aiming for a second consecutive NFC South title, running is central to being effective on offense in their remaining six games.

"Ever since I've been here, Coach Gruden always discusses how in November and December, the teams that run the ball are usually the teams that are successful," Williams said. "We have this stretch run, and I'm just ecstatic looking forward to it."

Graham's absence will be particularly glaring in short-yardage situations. The Bucs missed him in such circumstances Sunday, like in the first quarter when Dunn was stuffed for no gain on third and 1 and minus-2 yards on fourth and 1.

Gruden called Williams "a guy that can handle short yardage and goal line." Gruden said Askew is an option there too.

As for Smith, an undrafted rookie, his role remains unclear — he has lost a fumble in each of his first three games since being promoted from the practice squad last month. Smith couldn't pinpoint a reason for his struggles, and Gruden didn't exactly indicate he'll be patient.

"You know me well enough," Gruden said. "We don't fumble the ball here. We'll go back to basic fundamentals. We've got to do a better job taking care of the ball. The guy's a good player, an outstanding prospect. But he knows taking care of the ball is the No. 1 objective of anybody who touches the ball. You hold the organization in your hands every time you touch it."

The widespread uncertainty in the backfield raises an obvious question: Any second thoughts about releasing veteran back Michael Bennett last week?

"I don't live in hindsight," Gruden said.

There's no time to look back. With Graham out, the Bucs' biggest challenge lies ahead.